Commercially feasible process

Carbon and Graphite Fibers. Carbon and graphite fibers (qv) are valued for their unique combination of extremely high modulus and very low specific gravity. Acrylic precursors are made by standard spinning conditions, except that increased stretch orientation is required to produce precursors with higher tenacity and modulus. The first commercially feasible process was developed at the Royal Aircraft Fstablishment (RAF) in collaboration with the acrylic fiber producer, Courtaulds (88). In the RAF process the acrylic precursor is converted to carbon fiber in a two-step process. The use of PAN as a carbon fiber precursor has been reviewed (89,90). 

Polymerization. The first successful polymerizations of VDE in aqueous medium using peroxide initiators at 20—150°C and pressures above 30 MPa were described in a patent issued in 1948 (73). About a year later, the first copolymerizations of VDE with ethylene and halogenated ethylenes were also patented (74). After a hiatus of over 12 years a commercially feasible process was developed and PVDE was ready for market introduction (2). 

Because of the highly exothermic nature of acrylonitrile polymerization, bulk processes arc not normally used commercially. Howevei. a commercially feasible process lor bulk polymerization in a continuous stirred lank reactor has been developed. The heat nl reaction is controlled hy operating at relatively low conversion levels and supplementing the normal jacket cooling with reflux condensation of umcaclcd monomer... 

The homogeneous catalytic asymmetric hydrogenations of 2-arylacrylic acids have been studied. Both rhodium and ruthenium catalysts have been examined. The reaction temperatures and hydrogen pressures have profound effects on the optical yields of the the products. The presence of a tertiary amine such as triethylamine also significantly increases the product enantiomer excess. Commercially feasible processes for the production of naproxen and S-ibuprofen have been developed based on these reactions. 

In this paper we present a study of the catalytic asymmetric hydrogenation which leads to commercially feasible processes for the production of (S)-2-(6 -methoxy-2 -naphthyl)propionic acid (naproxen) and (S)-2-(p-isobutylphenyl)propionic acid (S-ibuprofen). 

Commercially Feasible Processes Based on the Asymmetric Hydrogenation of 2-Arvlacrvlic Acids. 

The ultimate goal in most industrial research is to develop economically attractive processes or products. The technology of asymmetric hydrogenation of 2-arylacrylic acids is probably most useful for the production of naproxen and S-ibuprofen. Naproxen is currently one of the top ten prescription drugs in the world S-ibuprofen is the active isomer in the popular anti-inflammatory drug ibuprofen. Figures 5 and 6 summarize two commercially feasible processes for the manufacturing of these products. 

The results showed that production of latices by radiation catalysis is a commercially feasible process. However, the authors did not appear to have resolved two process-development problems the reduction of residual monomer to commercially acceptable levels and the elimination of polymer build-up inside the process lines. Tbe authors noted, however, that these are problems of formulation and operation rather than of tbe basic process itself. 

Other gases are found on the surface of the earth and in the atmosphere. Methane (CH4), formerly known as marsh gas, is produced by bacterial processes, especially in swampy areas. It is a major constituent of natural-gas deposits formed over many millennia by decay of plant matter beneath the surface of the earth. Recovery of methane from municipal landfills for use as a fuel is now a commercially feasible process. Gases also form when liquids evaporate. The most familiar example is water vapor in the air from the evaporation of liquid water it provides the humidity of air. 

As hereinbefore pointed out, the 5-(tertiary alkyl)resorcinols thus prepared in accordance with this invention are important intermediates in the preparation of useful drugs. For example, 5-(l,l-dimethyl-heptyl)resorcinol is utilized in the preparation of l-hydroxy-3-(l,l-dimethylheptyl)-6,6a,7,8,9,l 0,10a-hexahydro-6,6-dimethyl-9H-dibenzo[b,d]pyran-9-one, which compound is extremely useful in the treatment of depression in humans, as described in U.S. Pat. Nos. 3,928,598, 3,944,673, and 3,953,603. Similarly, 5-(l,l-dimethyl-heptyl)resorcinol is required in the synthesis of3-(l,l-dimethylheptyl)-6a,7,8,9,10,10a-hexahydro-6,6-dimethyl-6H-dibenzo[b,d]pyran-l,9-diol, which compound is useful as a blood-pressure lowering agent. It can thus be seen that a commercially feasible process for preparing 5-(tertiary alkyl)resorcinols in high yield is desirable. 

Consider the sources of some of the common chemical raw materials and relate these to products that are accessible via one or two chemical transformations in a typical chemical complex. Starting with just a few simple components—air, water, salt (NaCl), and ethane—together with an external source of energy, quite a range of finished products is possible (Fig. 1.1). While it is unlikely that all of these will be produced at any one location, many will be, and all are based on commercially feasible processes [1]. Thus, a company which focuses on the electrolytic production of chlorine and sodium hydroxide from salt will often be sited on or near natural salt beds in order to provide a secure source of this raw material. A large source of freshwater, such as a river or a lake will generally be used for feedstock and cooling water... 

Both natural emetine and 2-dehydroemetine can be synthesised by commercially feasible processes, but in countries like India emetine is still extracted from plant material. 2-Dehydroemetine has not been able to replace emetine and today, as far as is known, it is being sold by only one pharmaceutical company. 

Catharanthus roseus is probably the most extensively studied plant for secondary metabolite production in cell cultures. As such it is an excellent model system however, the levels of alkaloids produced are still far below amounts necessary for a commercially feasible process. The technology for the large-scale culture of C. roseus cells is available. Future studies should thus focus on the regulation of alkaloid production, with the aim of eventually applying genetic engineering to increase alkaloid levels. 

The mechanical problems encountered and solved in developing catalytic cracking into a commercially feasible process were formidable and proved to be as important as the chemical problems. 

The first commercially feasible process for converting acrylic fibers to carbon fibers was developed by Walt, Phillips, and Johnson of the Royal Aircraft Establishment (RAE) in collaboration with the acrylic fiber producer, Courtaulds [621]. In the RAE process, the acrylic precursor is converted to carbon fiber in a two-step process [622]. Preoxidation or filament stabilization is carried out in the first stage. The precursor is heated in an oxygen atmosphere under tension at a temperature of approximately 200 250°C, well below its carbonizing temperature (approximately 800°C). At this temperature, the nitrile groups react with each other via a free radical addition process leading to the so-called ladder structure shown in reaction 12.34 [609,621 625]. 

The objective of the project was to develop a commercially feasible process for the manufacture of the monomer and polymer. This was accomplished. in two years time and in early 1960, the PVDP was ready for market introduction under the trademark KYNAR . Initial quantities of the KYNAR polymer, then called RC2525, were produced in a semiworks plant. In 1965, the first commercial plant for KYNAR resins began operations in Calvert City, Kentucky. 

Temperature has a profound effect on most reactions. In the first place, reaction rates usually increase with an increase in temperature, meaning that equihbrium is reached soonCT. Many gaseous reactions are sluggish or have imperceptible rates at room temperature but speed up enough at higher temperature to become commercially feasible processes. 

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